1. Field of the Invention
This invention relates to a plasma display panel, and more particularly to a plasma display panel that is adaptive for improving light-emission efficiency.
2. Description of the Related Art
Generally, a plasma display panel (PDP) is a display device utilizing a visible light emitted from a fluorescent body when an ultraviolet ray generated by a gas discharge excites the fluorescent body. The PDP has an advantage in that it has a thinner thickness and a lighter weight in comparison to the existent cathode ray tube (CRT) and is capable of realizing a high resolution and a large-scale screen. The PDP includes of a plurality of discharge cells arranged in a matrix pattern, each of which makes one pixel of a field.
FIG. 1 is a perspective view showing a discharge cell structure of a conventional three-electrode, alternating current (AC) surface-discharge PDP.
Referring to FIG. 1, a discharge cell 1 of the conventional three-electrode, AC surface-discharge PDP includes a first electrode 12Y and a second electrode 12Z provided on an upper substrate 10, and an address electrode 20X provided on a lower substrate 18. Such a discharge cell 1 is arranged at a panel in a matrix type as shown in FIG. 2.
On the upper substrate 10 provided with the first electrode 12Y and the second electrode 12Z in parallel, an upper dielectric layer 14 and a protective film 16 are disposed. Wall charges generated upon plasma discharge are accumulated into the upper dielectric layer 14. The protective film 16 prevents a damage of the upper dielectric layer 14 caused by a sputtering during the plasma discharge and improves the emission efficiency of secondary electrons. This protective film 16 is usually made from magnesium oxide (MgO).
A lower dielectric layer 22 and barrier ribs 24 are formed on the lower substrate 18 provided with the address electrode 20X. The surfaces of the lower dielectric layer 22 and the barrier ribs 24 are coated with fluorescent layers 26R, 26G and 26B. The address electrode 20X is formed in a direction crossing the first electrode 12Y and the second electrode 12Z. The barrier rib 24 is formed in parallel to the address electrode 20X to prevent an ultraviolet ray and a visible light generated by a discharge from being leaked to the adjacent discharge cells.
The fluorescent layers 26R, 26G and 26B are excited by an ultraviolet ray generated during the plasma discharge to generate any one of red, green and blue visible light rays. An inactive gas for a gas discharge is injected into a discharge space defined between the upper and lower substrate 10 and 18 and the barrier rib 24. A black matrix 30 is formed between the first electrode 12Y and the second electrode 12Z which are provided at the adjacent discharge cells 1.
Such an AC surface-discharge PDP drives one frame, which is divided into various sub-fields having a different discharge frequency, so as to express gray levels of a picture. Each sub-field is again divided into an initialization period for uniformly causing a discharge, an address period for selecting the discharge cell and a sustain period for realizing the gray levels depending on the discharge frequency. For instance, when it is intended to display a picture of 256 gray levels, a frame interval equal to {fraction (1/60)} second (i.e. 16.67 msec) is divided into 8 sub-fields SF1 to SF8 as shown in FIG. 2. Each of the 8 sub-fields SF1 to SF8 is divided into an address period and a sustain period. Herein, the initialization period and the address period of each sub-field are equal every sub-field, whereas the sustain period is increased at a ration of 2n (wherein n=0, 1, 2, 3, 4, 5, 6 and 7) at each sub-field. Since each sub-field has a different sustain period, it is able to express a gray scale of a picture.
In the reset period, a reset pulse is applied to the first electrode 12Y to cause a reset discharge. In the address period, a scanning pulse is applied to the first electrode 12Y and a data pulse is applied to the address electrode 20X, to thereby cause an address discharge between two electrodes 12Y and 20X. Upon address discharge, wall charges are formed at upper and lower dielectric layers 14 and 22. In the sustain period, an alternating current applied alternately to the first electrode 12Y and the second electrode 12Z generates a sustain discharge at the first electrode 12Y and the second electrode 12Z.
In such a conventional PDP, the red fluorescent layer 26R, the green fluorescent layer 26G and the blue fluorescent layer 26B are formed from a different material to thereby have a different dielectric constant. Accordingly, in order to generate a uniform address discharge at discharge cells, a driving voltage applied to each discharge should be set differently in consideration of dielectric constants of the fluorescent layers 26R, 26G and 26B.
However, in the conventional address period, all the discharge cells are supplied with a scanning pulse and a data pulse that have the same voltage level. Accordingly, dielectric constants of the red, green and blue fluorescent layers 26R, 26G and 26B cause a different address discharge is at each discharge cell. In other words, in the prior art, a uniformity of the discharge cell may be deteriorated, and an erroneous discharge may be generated in the sustain period due to wall charges formed differently for each discharge.
In order to compensate for the above-mentioned disadvantage, Korean Laid-open Patent Gazette No. 98-49446 has suggested a PDP as shown in FIG. 3.
Referring to FIG. 3, a three-electrode PDP according to another conventional embodiment includes a first electrode 34Y and a second electrode 34Z provided on an upper substrate 32, and an address electrode 42X provided on a lower substrate 40.
On the upper substrate 32 provided with the first electrode 34Y and the second electrode 34Z in parallel, an upper dielectric layer 36 and a protective film 38 are disposed. Wall charges generated upon plasma discharge are accumulated into the upper dielectric layer 36. The protective film 38 prevents a damage of the upper dielectric layer 36 caused by a sputtering during the plasma discharge and improves the emission efficiency of secondary electrons. This protective film 38 is usually made from magnesium oxide (MgO).
A lower dielectric layer 44 and barrier ribs 48 are formed on the lower substrate 40 provided with the address electrode 42X. The surfaces of the lower dielectric layer 44 and the barrier ribs 48 are coated with fluorescent layers 46R, 46G and 46B. The address electrode 42X is formed in a direction crossing the first electrode 34Y and the second electrode 34Z. The barrier rib 48 is formed in parallel to the address electrode 42X to prevent an ultraviolet ray and a visible light generated by a discharge from being leaked to the adjacent discharge cells.
The fluorescent layers 46R, 46G and 46B are excited by an ultraviolet ray generated during the plasma discharge to generate any one of red, green and blue visible light rays. An inactive gas for a gas discharge is injected into a discharge space defined between the upper and lower substrate 32 and 40 and the barrier rib 48.
In the PDP according to another conventional embodiment, a hole 50 is defined at an intersection between the address electrode 42X and the first electrode 34Y. Such a hole 50 is formed by removing the fluorescent layers 46R, 46G and 46B. Accordingly, an address discharge generated between the address electrode 42X and the first electrode 34Y is uniformly generated at all the discharge cells. In other words, since the fluorescent layers 46R, 46G and 46B are not formed at an intersection between the first address electrode 42X and the first electrode 34Y, an address discharge is generated irrespectively of dielectric constants of the fluorescent layers.
However, in the POP according to another conventional embodiment, since the fluorescent layers 46R, 46G and 46B are not formed at an intersection between the address electrode 42X and the first electrode 34Y, a light-emission efficiency of the sustain discharge generated between the first electrode 34Y and the second electrode 34Z is deteriorated. In other words, since the hole 50 is defined at a sustain discharge space, that is, since a coated area of the fluorescent body is reduced, it is impossible to excite the fluorescent body at a portion provided with the hole 50.
Accordingly, it is an object of the present invention to provide a plasma display panel that is adaptive for improving light-emission efficiency.
In order to achieve these and other objects of the invention, a plasma display panel according to one aspect of the present invention includes a plurality of electrode groups, each of which includes first and second electrodes formed adjacently to each other at an upper substrate and third electrodes having a large distance from the second electrodes; a plurality of address electrodes formed at a lower substrate in a direction crossing the first to third electrodes; barrier ribs provided to form a discharge space between the upper substrate and the lower substrate; a dielectric layer provided on the address electrode; a first area including a fluorescent layer formed on the dielectric layer; and a second area other than the first area.
In the plasma display panel, the second area is positioned at an intersection between the address electrode and the first electrode.
The second area has a large width than the address electrode.
The second area is defined from an intersection between the address electrode and the first electrode until the barrier ribs formed adjacently to the address electrode.
A black matrix is formed between the electrode groups.
The second area is defined from an intersection between the address electrode and the first electrode until the black matrix formed adjacently to the first electrode.
The second area has a larger width than the address electrode.
The second area is defined from an intersection between the address electrode and the first electrode until the barrier ribs formed adjacently to the address electrode.
A data pulse is applied to the address electrode and a scanning pulse is applied to the first electrode in an address period for selecting a cell to be turned.
A sustain pulse is alternately applied to the second electrode and the third electrode in a sustain period for discharging cells selected in the address period.
The fluorescent material is not formed at the second area.
A plasma display panel according to another embodiment of the present invention includes a plurality of first electrode groups, each of which includes first and second electrodes formed adjacently to each other at an upper substrate and third electrodes having a large distance from the second electrodes; a plurality of second electrode groups being adjacent to the first electrode groups and having first electrodes, second electrodes and third electrodes arranged in a mirror type with respect to the first electrode groups; a plurality of address electrodes formed at a lower substrate in a direction crossing the first to third electrodes; barrier ribs provided to form a discharge space between the upper substrate and the lower substrate; a dielectric layer provided on the address electrode; a first area including a fluorescent layer formed on the dielectric layer; and a second area other than the first area.
In the plasma display panel, the second area is positioned at an intersection between the address electrode and the first electrode.
The second area has a large width than the address electrode.
The second area is defined from an intersection between the address electrode and the first electrode until the barrier ribs formed adjacently to the address electrode.
A black matrix is formed between the first and second electrode groups.
The second area is positioned between the first electrodes formed adjacently with having the black matrix therebetween.
The second area has a larger width than the address electrode.
The second area is defined from an intersection between the address electrode and the first electrode until the barrier ribs formed adjacently to the address electrode.
A data pulse is applied to the address electrode and a scanning pulse is applied to the first electrode in an address period for selecting a cell to be turned.
A sustain pulse is alternately applied to the second electrode and the third electrode in a sustain period for discharging cells selected in the address period.
The fluorescent material is not formed at the second area.